Functional biaryl derivatives are important inductrial chemicals. They are used in the production of monomers for high performance and other polymers. For example, 3,3',4,4'-biphenyltetracarboxylic acid (BPTC), 4,4'-biphenyldicarboxylic acid and 4,4'-biphenol are monomers used in the manufacture of high performance polyimides, polyamides and polyesters. In addition, the biaryl derivatives are useful in the production of dyes, pharmaceuticals and agrochemical intermediates. These applications require very high purity (often above 99.9%) of the biaryl derivatives.